Heredity What are you made of

What is Diffusion? What is Osmosis? HUSTLE What is Diffusion? What is Osmosis? Explain what happens during Photosynthesis. Include where it takes place at. Explain what happens with Cellular Respiration. Include where it takes place at.

Traits offspring may have the same physical characteristics, or traits, as their parents because genetic information (DNA) is passed from parent to offspring during sexual reproduction.

Genes Each sex cell (egg or sperm) of the parent organism (plant or animal) contains one-half of the genetic material needed to create a new organism. Heredity is the passing of traits from one generation to another, or inheritance.

Chromosomes Chromosomes • A structure found in the nucleus of a cell that contains the genetic information (DNA).

Genes Genes • A segment of DNA found on a chromosome that determines the inheritance of a particular trait. • Genes are responsible for the inherited characteristics that distinguish one individual from another. • Genes for a specific trait generally come in pairs. • One gene from the pair is called an allele. • Genes may be expressed in two different forms. o Genotype—the set of genes carried by the organism. o Phenotype—the physical expression of the genes.

Genotype and Phenotype

Inherited traits Inherited traits • Characteristics that are passed from parent to offspring. Examples of inherited traits may be eye color, eye shape, hair type, or face shape. • Some inherited traits are dominant and some are recessive. o Dominant trait—A trait that will always be expressed in the phenotype. Alleles for dominant traits are represented by capital letters. o Recessive trait—A trait that will only be expressed in the phenotype if two recessive alleles are present. In the presence of a dominant trait, the recessive trait will not be expressed. Alleles for recessive traits are represented by lowercase letters.

Punnett Squares offspring inherit the genes for particular traits from their parents. • Genes for a particular trait normally come in pairs. • Since each parent normally has two alleles for a single trait, we use a Punnett square to determine the possibilities of the combinations of alleles that the offspring may receive. • A Punnett square is a tool used to predict the ratio or percentage of the possible genes that an offspring will have based on the genes of the parent.

More on Punnett Squares In a Punnett square, the top of the table shows the alleles provided by one parent. • The alleles for the other parent are placed along the left side of the table. • One allele from each parent is placed in the individual squares, forming a new gene pair. • The individual squares show the possibilities of allele pairs in the offspring. • For example, the following table shows the cross Tt x tt:

t T Tt tt • In this example, tallness (T) is the dominant trait and shortness (t) is the recessive trait. • As the Punnett square shows, TT, Tt, and tt are all possible genotypes for the height of the offspring. • The offspring with the genotypes TT and Tt will have a phenotype of tall; the offspring with the genotype of tt will have a phenotype of short. • If the two alleles are the same (TT or tt), the genotype is considered purebred. If the two alleles are different (Tt), the genotype is considered hybrid.

Example This example shows the inheritance of a single characteristic (height). A cross that shows the inheritance of a single characteristic is known as a monohybrid cross. • It is sometimes difficult to predict certain traits in humans (for example hair color or eye color) because there may be several different genes that control these traits.

Traits All characteristics that organisms have are inherited from their parents but some can be influenced by environmental factors.

Inherited traits An inherited trait is a genetically determined characteristic that distinguishes one organism from another organism. Some inherited traits are dominant, some are recessive, and some are neither. • An example of an inherited trait in plants may be color of flowers. The color red is dominant over the recessive color white. Pink flowers are a result of a blending of red and white. Other examples of inherited traits may be the shape of seeds or leaves, or the height of the plant.

Example of Inherited Traits • An example in animals may be eye color. Brown eye color is dominant over the recessive blue eye color. Green or hazel eyes are neither dominant nor recessive. Other examples of inherited traits may be body design, baldness, blood type, or skin color.

Inherited traits An inherited trait is a genetically determined characteristic that distinguishes one organism from another organism. Some inherited traits are dominant, some are recessive, and some are neither. • An example of an inherited trait in plants may be color of flowers. The color red is dominant over the recessive color white. Pink flowers are a result of a blending of red and white. Other examples of inherited traits may be the shape of seeds or leaves, or the height of the plant.

Inherited traits • An example in animals may be eye color. Brown eye color is dominant over the recessive blue eye color. Green or hazel eyes are neither dominant nor recessive. Other examples of inherited traits may be body design, baldness, blood type, or skin color.

Environmental factors Physical characteristics of organisms may be influenced by environmental factors. Examples of environmental factors that can alter the phenotype of an organism may be temperature, nutrients, injuries, disease, exposure to sun, or living conditions.

Environmental Factors • Temperature, for example, may affect the number or size of leaves in plants or the color or amount of fur or thickness of skin in animals. • Nutrients, for example, may affect the growth or seed production in plants or the weight or height in animals.

Environmental traits • Injuries, for example, may cause scarring in plants and animals. • Disease, for example, may affect the number of branches in plants or body shape in animals. • Exposure to sun, for example, may affect the color of leaves in plants or skin changes in animals. • Living conditions, for example, may affect the leaves, roots and height in plants or the condition of fur, skin, or teeth in animals.